THREE DIMENSIONAL TUNABLE FILTERS WITH AN ABSOLUTE CONSTANT BANDWIDTH AND METHOD

A tunable bandpass filter to provide a constant absolute bandwidth across the entire tuning range. The filter comprises of a plurality of tunable resonators, each having an enclosure. A resonating structure extending upwardly from the bottom surface of the enclosure and a tuning screw with a flat head extending downwardly from the top surface of the enclosure, wherein the resonating structure and the flat head of the screw face each other and form a gap. The height of the tuning screw can be adjusted to change the gap between the resonating structure and the flat head. The adjustable gap of the present filter allows for tunable filter operation.